Abstract 317: Nlrc5 Positively Regulates Intimal Formation via Interaction With PPARã in Vascular Smooth Muscle Cells

Background: Innate immunity and vascular smooth muscle cells play crucial role in the development of vascular remodeling and intimal hyperplasia. NLR family CARD domain containing 5 (Nlrc5), known as a pattern recognition receptor, has been noted for its implication in immune disease in recent studies. However, whether Nlrc5 regulates intimal hyperplasia is still unclear. Aim: We aimed to determine the role of Nlrc5 in intimal hyperplasia and its underlying molecular mechanism. Methods and Results: We showed that an elevated expression of Nlrc5 in neointima induced by carotid ligation compared normal carotid artery. In human aortic smooth muscle cells (HASMCs), PDGF induced Nlrc5 expression and nuclear translocation. By utilizing Nlrc5 knockout mice, we found Nlrc5 deficiency prominently aggravated neointimal formation compared to wild type (WT) mice. On the contrary, gain of function of Nlrc5 based on local adenovirus injection attenuated intimal hyperplasia. The neointimal area was comparable in WT mice receiving either WT or Nlrc5-/- bone marrow transplantation, demonstrating that hematopoietic cell-derived Nlrc5 did not affect vascular hyperplasia. In vitro experiments unveiled that knockdown of Nlrc5 resulted in excessive proliferation, migration and dedifferentiation of HASMCs. Nevertheless, depletion of Nlrc5 in HASMCs did not influence proinflammatory cytokine excretion and immune activation reflected by major histocompatibility complex-I expression. Mechanistic study revealed that Nlrc5 bound to nuclear transcription factor PPARγ and positively regulated PPARγ luciferase activity, ensuing contributing to KLF4 ubiquitination and degradation. Furthermore, we generated five deletion constructs of Nlrc5 and identified that the functional domain containing DD and NACHT constructs was responsible for the interaction with PPARγ. Conclusions: Our study reveals that Nlrc5 alleviates intimal formation through interaction with PPARγ and inhibition of smooth muscle cell dedifferentiation, suggesting that Nlrc5 constitutes a novel molecular target for vascular remodeling.